Photographic light-sensitive silver halide material

ABSTRACT

Photographic materials comprising a light-sensitive silver halide emulsion layer having in the emulsion layer or in an adjacent water-permeable layer a bisterazole compound having the formula: WHERE A stands for a chemical bond or a bivalent organic radical are described. These photographic materials have decreased fogging even under conditions of high temperature and humidity.

United States Patent Inventors Appl. No.

Filed Patented Assignee Priority Jozef Frans Willems Wilrijk;

Frans Clement Heugebaert, Kontich, both of Belgium Oct. 2, 1968 Oct. 26, 1971 Gevaert-AGFA N.V. Mortsel, Belgium Oct. 9, 1967 Great Britain PHOTOGRAPHIC LIGHT-SENSITIVE SILVER HALIDE MATERIAL 9 Claims, No Drawings U.S. Cl

Int. Cl

Field of Search References Cited UNITED STATES PATENTS 12/1942 Marines et a1 Dersch et al 2,531,832 11/1950 Stanton 96/66 2,533,990 12/1950 Blake 96/663 OTHER REFERENCES Finnegan et al., An Improved Synthesis of 5 Substituted Tetragoles. PP. 3908391 1,.1.A.C.S. 80, 1958.

Primary Examiner-William D. Martin Assistant Examiner-Bernard D. Pianalto Attorney-Alfred W. Breiner ABSTRACT: Photographic materials comprising a light-sensitive silver halide emulsion layer having in the emulsion layer or in an adjacent water-permeable layer a bisterazole compound having the formula:

where A stands for a chemical bond or a bivalent organic radical are described. These photographic materials have decreased fogging even under conditions of high temperature and humidity.

PHOTOGRAPHIC LIGHT-SENSITIVE SILVER HALIDE MATERIAL This invention relates to improved photographic materials comprising light-sensitive silver halide emulsions, more particularly to photographic materials which have less tendency to fog formation and which still possess the same light-sensitivity.

It is well known that light-sensitive silver halide materials comprising gelatin silver halide emulsion layers are subject to fogging. Fogging in general and chemical fogging in particular may be defined as the formation of a uniform deposit of silver on development which is dependent on a whole series of circumstances and factors namely on the nature of the emulsions, on their age, on the conditions under which they have been stored, on the development conditions, etc. For particular development conditions the fog tends to be greater as the time of storage and the temperature and relative humidity of the atmosphere in which the emulsions are stored are increased. Consequently it is known to carry out accelerated tests called incubation tests on the stability of photographic emulsions by storing them at an elevated temperature and a high humidity and then determining their sensitometric characteristics.

Addenda to the photographic material known as stabilizers or antifoggants protect the light-sensitive silver halide emulsions against formation and growth of fog particularly in highsensitive emulsions and in emulsions which are to be stored under conditions of high temperature and humidity as is for instance the case in tropical countries.

In accordance with the invention it has been found that the formation of fog in photographic light-sensitive silver halide materials can be avoided I by incorporating therein a bistetrazole compound corresponding to the following general formula:

wherein A represents a chemical bond or a bivalent organic group for example a carbon chain or heterocarbon chain, more particularly a bivalent saturated or olefinically unsaturated aliphatic group such as an alkylene group or an alkenylene group comprising from one to five carbon atoms, including such substituted aliphatic groups and such groups interrupted by one or more hetero atoms without adversely affecting the other properties of said materials.

This is rather surprising since it has been experienced, as is illustrated hereinafter in the examples, that the 5-alkylmonotetrazole monotetrazole compounds have no antifogging or stabilizing action at all. 7

Thus it would appear that the two -NH-moieties in the bistetrazole compounds are essential features of the compounds of the invention. By these two -NH-moieties the said bistetrazole compounds are bidentate ligands for forming complexes with silver i.e. they contain two coordinating atoms for silver namely the nitrogen atoms of said two -NH-moieties.

The following compounds are representative examples of compounds for use as antifoggants according to the present invention.

As is illustrated by the following preparations the bistetrazole compounds corresponding to the above general formula can be prepared amongst others by reaction in an or ganic solvent such as dimethyl formamide, dimethyl sulfoxide a'nd tetrahydrofuran of organic dinitriles with inorganic azides as described in Ann. 638 (1960) 69 and J.A.C.S. (1958) 3908.

Preparation 1 l,2-bis(tetrazolyl)-ethene A mixture of 26 g. (0.4 mole) of sodium azide, 21 g. (0.4 mole) of ammonium chloride and 15.6 g. (0.2 mole) of fumaronitrile in 200 cc. of dimethyl formamide was heated at C. for 24 hours. The sodium chloride formed was filtered by suction and the filtrate concentrated by evaporation. The residue was dissolved in 100 m]. of water whereupon the pH was adjusted to 9. The solution was extracted with ether and the aqueous layer acidified to pH 2. The crystallized bistetrazole was filtered by suction. Melting point: 230 C. Preparation 2 l,3H-bis(tetrazolyl)-propane A mixture of 26 g. (0.4 mole) of sodium azide, 21 g. (0.4 mole) of ammonium chloride and 18.8 g. (0.2 mole) of glutaronitrile in 200 cc. of dimethyl formamide was heated with stirring at 100 C. for 72 hours. The sodium chloride formed was filtered by suction and the filtrate concentrated by evaporation. The residue was recrystallized from 200 cc. of water. Melting point: 193C.

The antifoggants are generally incorporated into the silver halide emulsion layer of the light-sensitive material. The way in which the compounds of use according to the invention are added to emulsions is not critical and the addition can be made during no matter what step of emulsion preparation; they can be added before or after the emulsion has been optically sensitized, preferably just before coating of the emulsion on a suitable support such as, for example, paper, glass, or film. The method of addition used will depend largely on the solubility of the chosen antifoggant. In general it is preferable to dissolve the antifoggant in water or a water-miscible solvent not injurious to the emulsion such as dimethyl formamide, dimethyl sulphoxide, tetrahydrofuran, acetone, ethanol and add the solution to the emulsion. Another method useful for water-insoluble antifoggants is that sometimes used for incorporating color couplers, and comprises dissolving the compound in a water-immiscible solvent or a mixture of a waterimmiscible and water-miscible solvent, dispersing the resultant solution in aqueous gelatin and adding the dispersion to the emulsion and occasionally removing the solvent(s) employed in either order. In this connection reference is made to U.S. Pat. No. 2,304,940 to U.l(. Pats. 791,219, 1,098,594, 1,099,414, 1,099,415, 1,099,416, 1,099,417, and to the published Dutch Pat. application 6714713.

Instead of incorporating the compounds of the invention into the emulsion layer they can also be incorporated into another layer of the photographic material, e.g. a gelatin antistress layer or intermediate layer, which is in water-permeable relationship with the said emulsion layer or into one of the 0 sensitized or nonsensitized silver halide emulsion layer, a

silver halide emulsion layer of use in diffusion transfer processes for the production of silver images, an X-ray emulsion layer, and an emulsion layer sensitive to infrared radiation. They may be incorporated into high-speed negative materials as well as into rather low-speed positive materials. Various silver salts may be used as light-sensitive salt, e.g., silver bromide, silver iodide, silver chloride, or mixed silver halides, e.g., silver chlorobromide or silver bromoiodide.

The silver halides are dispersed in the common hydrophilic colloids such as gelatin, casein, zein, polyvinyl alcohol carboxymethyl cellulose, alginic acid, etc., gelatin being, however, favored.

The amount of antifoggant employed in the light-sensitive silver halide material depends on the particular type of emulsion and the desired effect and can vary within very wide limits. The optimum amount of antifoggant to be added is best determined for each particular type of emulsion by trial. Generally, the most suitable concentration is between 0.05

polymers may be of various types. Various derivatives of alkylene oxides may be used to sensitize the silver halide emulsions, e.g., alkylene oxide condensation products as described among others in U.S. Pat. Nos. 2,531,832 and 2,533,990 in U.K. Pats. 920,637, 940,051, 945,340, and 991,608 and in Belgian Pat. 643,710. Other compounds that sensitize the emulsion by development acceleration and that are suitable for use in combination with the antifoggants of use according to the invention are the onium derivatives of amino-N-oxides as described in U.K. Pat. No. 1,121,696.

The stabilizers according to the invention can also be used in conjunction with other known stabilizers, for instance, with heterocyclic nitrogen containing thioxo compounds such as benzothiazoline-Z-thione and l-phenyl-2-tetrazoline-S-thione with mercury compounds such as those described in Belgian Pat. Specifications 524,121 and 677,337 and in the published Dutch Pat. Application 6715932 and preferably with compounds of the hydroxytriazolopyrimidine type (azaindolizines), particularly in extreme storage and development circumstances.

In the following examples the stabilizing and fog-inhibiting action of the bistetrazole compounds corresponding to the above general formula is illustrated by incubation tests on photographic materials incorporating said compounds.

EXAMPLE 1 A series of eight identical conventional photographic gelatino silver bromoiodide emulsions (4.5 moles percent iodide) comprising the common emulsion addenda such as hardening agents, coating aids, sensitizing dyes, etc. was prepared. To each of these emulsions, except for one, was added a tetrazole compound as listed in the table below in the given concentration. Then the emulsions were coated on a conventional support and dried.

The values of speed, gradation, and fog of the materials formed were determined shortly after preparation and after incubation for 5 days at 57 C. and 34 percent relative humidity and the relative increase or decrease in said values for each material is listed in the table below.

Development took place for 8 min. at 20 C. in a fine-grain developer having the following composition:

millimole and 20 millimoles of antifoggant per mole of silver Wale 800 ccs halide p-monomethylaminophenol sulfate 1.5 g

sodium sulfite (anhydrous) 100 g. The light-sensitive emulsions may be chemically as well as max g optically sensitized. They may be chemically sensitized by efboric acid 5 g, fectin g the ripening in the presence of small amounts of sulfurbmmde water to make 1 000 ccs containing compounds such as allylthrocyanate, allylthiourea,

TABLE Material Compound added Concentration per A fog A gra- A speed kg. of emulsion datlon I II A None +0. 24 -0. 3O 0 +6 4 39mg. (0.2mmole).. +0.02 0. 12 0 +7 0 1. 30mg. (0.2mm0le) +0.02 0. 12 -13 1 D 5.. 33 mg. (0.21nn1ole) +0.04 0. 12 13 7 E- "do +0.01 0. 12 -7 0 F- 3 36 mg. (0.2 mmole) +0.03 +0.01 +3 +2 G 5-methyltetrazo1e. 17 mg. (0.2 mmole) +0. 28 0. 24 8 +23 H.-. do 84 mg. (1 mmole) +0.31 0. 25 1 +26 sodium thiosulfate, etc. The emulsions may also be sensitized by means of reductors, for instance, tin compounds as described in our British Pat. Specification 789,823 and small amounts of noble metal compounds such as of gold, platinum, palladium, iridium, ruthenium, and rhodium.

Other addenda such as hardening agents, wetting agents, plasticizers, color couplers, developing agents and optical sensitizers can be incorporated into the emulsion in theusual way.

The antifoggants according to the present invention are particularly suitable for use in conjunction with compounds which sensitize the emulsion by development acceleration, for

example, alkylene oxide polymers. These alkylene oxide 7 5 ing with a density 0.1 above fog and a density 1 above fog respectively. A decrease by 30 means a doubling of the speed while an increase by 30 means a halving ofthe speed.

EXAMPLE 2 Example 1 was repeated with the difference however that now the development occurred at 20 C. for 5 min. in a developing solution having the following composition:

water 800 ccs. p-monomethylaminophenol sulfate 1.5 g. sodium sulfite (anhydrous) 50 g.

hydroquinone sodium carbonate (anhydrous) 32 g. potassium bromide 2 g. war rp 3 1,000 ccs.

The followingsensitometric results were obtained after an 7 incubation period of 5 days at 57 C. and 34 percent of relative humidity.

The values given for the speed are exposure values corresponding with density 0.1 above fog and density 1 above fog respectively. A decrease of the value by 30 means a doubling of the speed.

The results show that the bistetrazole compounds have usefully reduced the fog due to incubation (compare with materials A and G). I

We claim:

1. Photographic material comprising a support and at least one light-sensitive silver halide emulsion layer comprising in said emulsion layer or in at least one water-permeable layer coated at the same side of the support as the said emulsion layer at least one bistetrazole compound corresponding to the following general formula:

H N N/ A-C l i wherein A stands for a bivalent organic radical.

2. Photographic light-sensitive silver halide material according to claim 1, wherein A stands for a bivalent aliphatic saturated or olefinically unsaturated group or such bivalent group interrupted by one or more heteroatoms.

3. Photographic light-sensitive silver halide material according to claim 1, wherein A stands for an alkylene or alkenylene group comprising at most 5 carbon atoms.

4. Photographic light-sensitive silver halide material according to claim 1, wherein said bistetrazole compound is present in the light-sensitive silver halide emulsion layer in an amount between 0.05 and 20 millimoles per mole of silver halide.

5. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a stabilizer of the hydroxytriazolopyrimidine type.

6. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a development accelerator of the polyoxyalkylene type.

7. Photographic material according to claim 1 wherein said material comprises a support coated with water-permeable colloid layers including a light-sensitive silver halide emulsion layer and said bistetrazole compound is introduced into said material after its exposure to light during development.

8. Photographic material of claim 7 wherein a hydroxytriazolopyrimidine compound is introduced into said material at the same time as said bistetrazole.

9. Photographic material of claim 7 wherein a polyoxyalkylene compound is introduced into said material at the same time as said bistetrazole.

C l l 

2. Photographic light-sensitive silver halide material according to claim 1, wherein A stands for a bivalent aliphatic saturated or olefinically unsaturated group or such bivalent group interrupted by one or more heteroatoms.
 3. Photographic light-sensitive silver halide material according to claim 1, wherein A stands for an alkylene or alkenylene group comprising at most 5 carbon atoms.
 4. Photographic light-sensitive silver halide material according to claim 1, wherein said bistetrazole compound is present in the light-sensitive silver halide emulsion layer in an amount between 0.05 and 20 millimoles per mole of silver halide.
 5. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a stabilizer of the hydroxytriazolopyrimidine type.
 6. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a development accelerator of the polyoxyalkylene type.
 7. Photographic material according to claim 1 wherein said material comprises a support coated with water-permeable colloid layers including a light-sensitive silver halide emulsion layer and said bistetrazole compound is introduced into said material after its exposure to light during development.
 8. Photographic material of claim 7 wherein a hydroxytriazolopyrimidine compound is introduced into said material at the same time as said bistetrazole.
 9. Photographic material of claim 7 wherein a polyoxYalkylene compound is introduced into said material at the same time as said bistetrazole. 